xkcd, sometimes stylized as XKCD,[‡ 1] is a webcomic created by Randall Munroe. The comic's tagline describes it as a "A webcomic of romance, sarcasm, math, and language"[2] (formerly a "Stick-figure strip featuring humour about technology, science, mathematics and relationships").[3] Munroe states on the comic's website that the name of the comic is not an acronym but "just a word with no phonetic pronunciation".

The subject matter of the comic varies from statements on life and love to mathematical and scientificin-jokes. Some strips feature simple humor or pop-culture references. Although it has a cast of stick figures,[4][5] the comic occasionally features landscapes, intricate mathematical patterns such as fractals (for example, strip No. 17 "What If"[‡ 2] shows an Apollonian gasket), intricate graphs and charts, or imitations of the style of other cartoonists (as during "Parody Week").[6]

xkcd is available under the Creative Commons Attribution-NonCommercial 2.5 License.[‡ 3] New comics are added three times a week, on Mondays, Wednesdays, and Fridays,[‡ 1][7] although on some occasions they have been added every weekday.

Since July 2012, there has been a branch of xkcd called xkcd What-If, which answers unusual reader-submitted science questions in a light-hearted but scientifically grounded way.[8]What If? is presented in the format of an article rather than a comic strip.[9][10]

The comic began in September 2005 when Munroe decided to scan doodles from his school notebooks and put them on his webpage. Eventually the comic was split off into its own website, where Munroe started selling T-shirts based on the comic. He currently works full-time on the comic, making Munroe one of the few professional webcomic artists.[‡ 1][11]

According to Munroe, the comic's name has no particular significance and is simply a four-letter word without a phonetic pronunciation, something he describes as "a treasured and carefully guarded point in the space of four-character strings." The name of the comic is spelled in all lowercase letters, or all capitals.[‡ 1]

In May 2007, the comic garnered widespread attention by depicting online communities in geographic form.[12] Various websites were drawn as continents, each sized according to their relative popularity and located according to their general subject matter.[12] This put xkcd at number two on the Syracuse Post-Standard's "The new hotness" list.[13]

In October 2008, The New Yorker magazine online published an interview and "Cartoon Off" between Randall Munroe and Farley Katz. For the "Cartoon-Off", Katz and Munroe each drew: "the Internet, as envisioned by the elderly", "String Theory", "1999", and "your favorite animal eating your favorite food".[14]

On September 19, 2012, comic No. 1110 ("Click and Drag"), featured a panel which can be explored via clicking and dragging its insides.[‡ 8] It immediately triggered positive response on social websites and forums.[15] The large image measures 165,888 pixels wide by 79,822 pixels high.[16]

Comic No. 1190 ("Time") began publication at midnight EDT on March 25, 2013, with the comic's image updating every 30 minutes until March 30, when they began to change every hour, lasting for over four months. The images constitute time lapseframes of a story, with the mouseover text originally reading "Wait for it.", later changed to "RUN." and changed again to "The end." on July 26. The story began with a male and female character building a sandcastle complex on a beach who then embark on an adventure to learn the secrets of the sea. On July 26, the comic superimposed a frame (3094) with the phrase "The End". Tasha Robinson of The A.V. Club wrote of the comic: "[...] the kind of nifty experiment that keeps people coming back to XKCD, which at its best isn't a strip comic so much as an idea factory and a shared experience".[17]Cory Doctorow mentioned "Time" in a brief article on Boing Boing on April 7, saying the comic was "coming along nicely". The 3,099-panel "Time" comic ended on July 26, 2013, and was followed by a blog post summarizing the journey.[18]

A large number of the strips contain mathematics or computer science jokes. These jokes often feature university-level subjects, although many are written in such a way that a clear understanding of the subject is not required to get the punch line.

Romance is another subject often visited in the comic, with many strips not intended to be humorous;[20] Munroe is a self-declared fan of artist Kurt Halsey's bleak romances. There are also many strips opening with "My Hobby:" and usually depicting the nondescript narrator character describing some type of humorous or quirky behavior often involving language games.[‡ 10][‡ 11][‡ 12][‡ 13]

"Malamanteau",[‡ 14] with mouseover text "The article has twenty-three citations, one of which is an obscure manuscript from the 1490s and the other twenty-two are arguments on Language Log."

Although Munroe does not maintain a list of characters on his web site, some recurring characters can be identified by their visual features (for example, hats) and mannerisms.

Black Hat, or Black Hat Guy, a man who looks like a normal stick-figure xkcd character, but for the addition of a black hat, a reference to Aram from the now-defunct webcomic Men in Hats, not to black hat hackers as is often supposed.[26][‡ 32] This character first appeared in the comic "Poisson" (the twelfth comic published on the website).[‡ 33] The character refers to himself as a "Classhole" (a portmanteau of "classy" and "asshole").[‡ 34] He does not shy from pointing out the failures of others and has at times used extreme violence in order to emphasize a point.[‡ 35][‡ 36] In the January 30, 2008 comic, his hat was taken by a woman, though he later retrieved it by stealing a submarine and using it to crash through the ice where she was skating. The character is one of the most frequently occurring in the comic, though he remains unnamed (he was referred to in multiple comics as "hat guy").[‡ 32][‡ 37]

In the "Secretary" story arc, Black Hat is nominated for the post of Secretary of the Internet when the Internet starts to collapse. After a variety of hijinks involving Ron Paul, Cory Doctorow, and the Auto-Troll Shuffle (described by him as taking a whole car apart, swapping the parts with the same parts of random cars in the same parking lot, and then building a new car out of them), he is sentenced to death. He escapes by filling the Capitol rotunda with plastic ball pit-style balls, distracting his pursuers while he flees on Doctorow's hot-air balloon.[‡ 38] Since comic 433 "Journal 5" he has been in a relationship with "psychotic female". His apartment is outfitted with a moat.[‡ 39]

A recurring female character, known as Megan. She is first referred to by name in comic No. 159 – "Boombox",[‡ 40] and again several times afterward,[‡ 41][‡ 42][‡ 43] although she may have appeared earlier as an unnamed character notably in comic No. 108 - "M.C. Hammer Slide".[‡ 44] She is recognized by her short, dark hair.

A beret-wearing male often referred to as Beret Guy, existentialist and eccentric who displays a charming, childlike optimism and naivete. He is first seen in the "Nihilism" comic,[‡ 45] and often has odd behaviors, ideas and activities underway.

Psychotic female, distinguished by long dark hair, a general proximity to Black Hat Guy and a tendency towards excessive violence, both verbal and physical. Her first appearance is in comic 377, "Journal 2".[‡ 46] She has been a recurring character since then, in some form of relationship with the equally psychotic Black Hat Guy, causing chaos, damage, vandalism and abuse with no apparent remorse or reason.

A similar character appeared earlier in comic 177, "Alice and Bob", where she is referred to as "Eve".[‡ 47]

A boy in a barrel appeared in five early strips. Unlike most other characters, he is not a stick figure.[‡ 48] He was repeatedly seen inside a barrel, floating in a large body of water. The boy in the barrel was one of many doodles in the older comics, but has not been seen since comic No. 31, in which he flew away with a ferret wearing a toy airplane.[‡ 49]

A pet ferret with wings similar to a plane's on its back with the rudders of a plane's tail on its tail appeared in comics including Barrel – Part 5[‡ 49] and a guest comic.[‡ 50]

Mrs. Roberts was a main character in the "1337"[‡ 57] series, and has appeared in other comics along with her children, Robert'); DROP TABLE Students;-- aka "Little Bobby Tables" (a reference to SQL injection), and Elaine Roberts (although her first name is really "Help I'm trapped in a drivers license factory"), the protagonist of the "1337" series.[‡ 58][‡ 59][improper synthesis?]

Firefly character River Tam—and actress Summer Glau, who played her—has appeared in a few comics, usually in a dream sequence where a character in the strip makes reference to her.[‡ 60] Other Firefly cast members, such as Nathan Fillion, have appeared in the series;[‡ 30] many turn out to have similar personalities to their Firefly characters.

YouTube has placed a feature on comments that plays back the comment aloud on "Audio Preview", possibly based on the strip "Listen to Yourself".[‡ 70][35][36]

Running the following code is an easter egg in Python 2.7 and on: import antigravity, inspired by the strip "Python".[‡ 71][37] In Python 3, the module also contains a geohashing function, and in 3.4, Python opens the page of the comic when run with no other code.

In the xkcd cartoon "Troll Slayer",[‡ 72]4chan's /b/ boards are taken over by Twilight lovers. In response to this, /b/ was temporarily renamed "Twilight Appreciation Station", and included the text "We have met the enemy and he is us", which appears in the cartoon as a note added by Randall Munroe. In order to prevent /b/ from trolling the xkcd forums, registration was blocked for several days after the comic appeared.

In November 2010, in response to the comic "Malamanteau", several Wikipedia editors attempted to create a Wikipedia article of the same name, which led to a large debate about what does and does not belong in the encyclopedia.[38]

Based on "Packages",[‡ 76] programmers set up programs to automatically find an item for sale on the Internet for $1.00 every day.[42][43]

"Rule 34"[‡ 77] has the characters commenting on the lack of pornography featuring women in the shower playing electric guitar. Randall Munroe subsequently created the website WetRiffs.com, which hosts submitted pictures of men and women in showers playing guitars.[‡ 78]

In response to "Password Strength",[‡ 79]Dropbox shows two messages reading "lol" and "Whoa there, don't take advice from a webcomic too literally ;)" when attempting to register with the password "correcthorsebatterystaple".[44]ArenaNet recommended that Guild Wars 2 users create passwords following the guidelines of the same comic.[45]

Following "Approximations",[‡ 80] the equation for the White House switchboard constant described in the comic was added to WolframAlpha database.[46]

xkcd has been recognized at the Web Cartoonists' Choice Awards. In the 2008 Awards, it was nominated for "Outstanding Use of the Medium", "Outstanding Short Form Comic", and "Outstanding Comedic Comic", and won "Outstanding Single Panel Comic".[49]xkcd was also voted Best Comic Strip by readers in the 2007 Weblog Awards[50] and 2008 Weblog Awards.[51] It was also nominated for a 2009 NewNowNext Award in the category 'OMFG Internet Award'.[52][53] Randall Munroe was nominated for the Hugo Award for Best Fan Artist in both 2011 and 2012.[54][55] He won a Hugo Award for Best Graphic Story in 2014, for "Time".[56]

xkcd comics have been translated into a number of languages. One group of readers has translated the first 729 comics into French[‡ 82] and nearly half of the comics have been translated into Russian.[‡ 83] One reader has translated many of the comics into Spanish; translations exist for comics that, according to the translator, can be translated without losing their humor.[‡ 84] Various xkcd comics have also been translated into German,[‡ 85] Finnish,[‡ 86] Czech,[‡ 87] Portuguese,[‡ 88] Esperanto,[‡ 89]Lojban,[‡ 90] and Yiddish.[‡ 91]

In September 2009, Munroe released a book, entitled xkcd: volume 0, containing selected xkcd comics.[‡ 92] The book was published by breadpig, under a Creative Commons license, CC BY-NC 3.0,[57] with all of the publisher's profits donated to Room to Read to promote literacy and education in the developing world. Six months after release, the book had sold over 25,000 copies. The book tour in New York City and Silicon Valley was a fundraiser for Room to Read that raised $32,000 to build a school in Salavan Province, Laos.[58][59]

In October 2012, xkcd: volume 0 was included in the Humble Bundle eBook Bundle. It was available for download only to those who donated higher than the average donated for the other eBooks. The book was released DRM-free, in two different-quality PDF files.[60]

On March 12, 2014, Randall Munroe announced the book What If?: Serious Scientific Answers to Absurd Hypothetical Questions. The book was released September 2, 2014. The book expands on the What-If series on the website.[‡ 93][61]